Question: This British mystery bird is easy to identify, so I am making up for that by asking a difficult question about it, a question that will especially appeal to the mathematics buffs out there: how fast is this bird moving in this image? How did you figure it out? (Yes, do show your work so the rest of us can follow how you made your calculations!) Can you identify this bird's taxonomic family and species?

Response: This is an adult coal tit, Periparus ater, a member of Paridae, the family of tits, chickadees, and titmice. This passerine family is found throughout much of the world, including in much of Eurasia, sub-Saharan Africa and in North America, where they range as far south as southern Mexico.

The coal tit is a sedentary species in temperate humid conifer forests of all sorts throughout its range [range map], although they may move locally in response to extreme weather conditions. Birds in the far north of their range do migrate.

In winter, coal tits form small flocks with other tits. They have similar feeding preferences and habits, gleaning insects from tree bark and eating seeds. They are especially fond of suet and black oil sunflower seeds.

Coal tits are cavity nesters, and nest low down in old rotting stumps, cracks in walls, burrows of small animals or in nest boxes provided by bird-friendly humans.

This species is gregarious and will form mixed species flocks with other tits in winter. In this image, the coal tit can be easily distinguished from the march tit, Poecile palustris, by the large black throat patch and the buff-yellow underparts.

Coal tit - smallest of the UK tits, apparently. They seem to know their place in the tit pecking order. They leave a feeding port if a blue, great or long-tail tit enters their personal space. Sometimes they fly off completely, sometimes they retreat to a safe distance and await their turn. Not the most colourful. One of the main field marks is the white splodge on the nape, but this view doesn't show it.

To answer the question I asked, according to my calculations, this bird is moving at 0.8 metres per second in this image. [(2 mm)(400s)/1000].